import { useEffect, useMemo, useState } from 'react';
import { useQuery } from '@tanstack/react-query';
import { api, runReportExportUrl, type HarnessGateNode, type HarnessGateStatus, type HarnessTraceGraph } from '../../lib/api';
import { Card, StatusBadge } from '../ui/Card';

const NODE_TONE: Record<HarnessGateStatus, string> = {
  queued: 'border-slate-200 bg-slate-50 text-slate-500',
  running: 'border-blue-300 bg-blue-50 text-blue-800 shadow-[0_0_0_4px_rgba(59,130,246,0.1)]',
  pass: 'border-emerald-300 bg-emerald-50 text-emerald-800',
  warning: 'border-amber-300 bg-amber-50 text-amber-800',
  blocked: 'border-rose-400 bg-rose-50 text-rose-800 shadow-[0_0_0_4px_rgba(244,63,94,0.09)]',
  error: 'border-rose-400 bg-rose-50 text-rose-800 shadow-[0_0_0_4px_rgba(244,63,94,0.09)]',
  skipped: 'border-slate-200 bg-slate-100 text-slate-400',
};

const STATUS_MARK: Record<HarnessGateStatus, string> = {
  queued: '○',
  running: '●',
  pass: '✓',
  warning: '!',
  blocked: '×',
  error: '×',
  skipped: '–',
};

function Evidence({ node }: { node: HarnessGateNode }) {
  const entries = Object.entries(node.evidence);
  return (
    <div className="grid gap-4 lg:grid-cols-[minmax(0,1fr)_minmax(18rem,0.8fr)]">
      <div>
        <div className="flex flex-wrap items-center gap-2">
          <h3 className="text-lg font-semibold text-slate-900">{node.title}</h3>
          <StatusBadge value={node.status} />
        </div>
        <p className="mt-1 text-sm text-slate-500">{node.description}</p>
        <div className="mt-4 rounded-xl border border-slate-200 bg-slate-50 p-4">
          <div className="text-xs font-semibold uppercase tracking-[0.12em] text-slate-400">Latest decision</div>
          <p className="mt-2 text-sm leading-6 text-slate-700">{node.reason}</p>
          {node.updated_at && <p className="mt-2 text-xs text-slate-400">{node.updated_at.replace('T', ' ').replace('Z', '')}</p>}
        </div>
      </div>
      <div className="rounded-xl border border-slate-800 bg-slate-950 p-4 text-slate-100">
        <div className="text-xs font-semibold uppercase tracking-[0.12em] text-slate-400">Safe evidence</div>
        {entries.length > 0 ? (
          <dl className="mt-3 space-y-2 text-xs">
            {entries.map(([key, value]) => (
              <div key={key} className="grid grid-cols-[8rem_minmax(0,1fr)] gap-3 border-b border-slate-800 pb-2 last:border-0">
                <dt className="font-medium text-slate-400">{key}</dt>
                <dd className="break-all font-mono text-slate-200">{typeof value === 'string' ? value : JSON.stringify(value)}</dd>
              </div>
            ))}
          </dl>
        ) : <p className="mt-3 text-sm text-slate-500">No evidence has been emitted for this gate yet.</p>}
      </div>
    </div>
  );
}

export function TraceExplorer({ traceId, onClose }: { traceId: string; onClose?: () => void }) {
  const query = useQuery({
    queryKey: ['trace-graph', traceId],
    queryFn: () => api.traceGraph(traceId),
    enabled: Boolean(traceId),
  });
  const [graph, setGraph] = useState<HarnessTraceGraph | null>(null);
  const [selectedId, setSelectedId] = useState('H1-context');

  useEffect(() => {
    if (query.data) setGraph(query.data);
  }, [query.data]);

  useEffect(() => {
    if (!traceId) return undefined;
    return api.watchTrace(traceId, setGraph);
  }, [traceId]);

  const selected = useMemo(
    () => graph?.nodes.find((node) => node.id === selectedId) ?? graph?.nodes[0] ?? null,
    [graph, selectedId],
  );

  return (
    <Card
      title="Harness trace explorer"
      right={<div className="flex items-center gap-2">
        <a href={`/reports/h6?run=${encodeURIComponent(traceId)}`} className="rounded-lg border border-indigo-200 bg-indigo-50 px-3 py-1.5 text-xs font-semibold text-indigo-700 transition hover:bg-indigo-100">Open H6</a>
        <a href={runReportExportUrl(traceId, 'html')} className="rounded-lg bg-slate-900 px-3 py-1.5 text-xs font-semibold text-white transition hover:bg-slate-700">Export evidence</a>
        {onClose && <button type="button" onClick={onClose} className="rounded-lg border border-slate-200 px-3 py-1.5 text-xs font-medium text-slate-600 transition-colors hover:bg-slate-50">Close</button>}
      </div>}
      className="overflow-hidden"
    >
      <div className="mb-5 flex flex-wrap items-end justify-between gap-3">
        <div>
          <p className="text-[11px] font-semibold uppercase tracking-[0.13em] text-slate-400">Trace ID</p>
          <p className="mt-1 break-all font-mono text-sm text-slate-700">{traceId}</p>
        </div>
        <div className="flex items-center gap-2 text-xs text-slate-500">
          <span className={`h-2 w-2 rounded-full ${graph?.terminal ? 'bg-emerald-500' : 'animate-pulse bg-blue-500'}`} />
          {graph?.terminal ? 'Completed' : 'Live · waiting for events'}
          <span className="text-slate-300">·</span>
          {graph?.progress ?? 0}/7 gates
        </div>
      </div>

      {query.isLoading && !graph ? <div className="py-10 text-center text-sm text-slate-500">Loading trace…</div> : (
        <>
          <div className="overflow-x-auto pb-5">
            <div className="flex min-w-max items-center px-1 py-3">
              {graph?.nodes.map((node, index) => {
                const next = graph.nodes[index + 1];
                const edgeActive = node.status === 'pass' || node.status === 'running' || node.status === 'warning' || next?.status === 'running';
                return (
                  <div key={node.id} className="flex items-center">
                    <button
                      type="button"
                      aria-pressed={selectedId === node.id}
                      onClick={() => setSelectedId(node.id)}
                      className={`w-40 rounded-xl border p-3 text-left transition duration-200 hover:-translate-y-0.5 hover:shadow-md ${NODE_TONE[node.status]} ${selectedId === node.id ? 'ring-2 ring-slate-900/10' : ''}`}
                    >
                      <div className="flex items-center justify-between gap-2">
                        <span className="text-xs font-bold tracking-wide">{node.title.split(' · ')[0]}</span>
                        <span className={`flex h-6 w-6 items-center justify-center rounded-full border border-current text-xs ${node.status === 'running' ? 'animate-pulse' : ''}`}>{STATUS_MARK[node.status]}</span>
                      </div>
                      <div className="mt-3 text-sm font-semibold">{node.title.split(' · ')[1]}</div>
                      <div className="mt-1 truncate text-[11px] opacity-70">{node.reason}</div>
                    </button>
                    {next && <div className={`trace-edge mx-2 ${edgeActive ? 'trace-edge-active' : ''}`} aria-hidden="true" />}
                  </div>
                );
              })}
            </div>
          </div>
          {selected && <Evidence node={selected} />}
          {!graph?.found && <div className="mt-4 rounded-xl border border-amber-200 bg-amber-50 p-3 text-sm text-amber-800">This is a legacy or not-yet-started trace. New chat turns emit detailed H1–H7 events automatically.</div>}
        </>
      )}
    </Card>
  );
}